BK POLYOMAVIRUS-ASSOCIATED UROTHELIAL CARCINOMA OF THE BLADDER IN KIDNEY TRANSPLANT RECIPIENTS – A RETROSPECTIVE LOOK OVER A 50 YEAR PERIOD.

Introduction:

Renal transplant recipients are at an increased risk of malignancies. Urothelial carcinoma is not an uncommon malignancy among renal transplant recipients accounting for 12-51% of all malignancies in this setting with significant regional variations. The association of BK polyoma virus(BKPyV) with urothelial cancer (UC) has been described in the past with around 40 cases of UC developing in association with BKPyV being described in literature so far. Histologically, it shows high-grade urothelial carcinoma  with a high frequency of glandular differentiation and micropapillary structures  and positive immunohistochemistry for polyomavirus large T antigen, p53and p16

Methods:

From a retrospective database of malignancies occurring among renal allograft recipients at  our center, we identified all cases of urothelial cancers of the bladder. Tissue blocks of the urothelial cancers were retrieved. An immunohistochemistry (IHC) for SV 40 antigen was done on the retrieved tissue blocks, to identify SV40 staining in the urothelial cancer. Further clinical details of the cases were retrieved from electronic medical records and medical case files.

Results:

In this database of  3807 patients who underwent renal transplant at our center from 1971 to 2021, there were 107 cases of malignancy in the post transplant period. 7 cases of urothelial cancer of the bladder were identified from among this cohort.  IHC for SV 40 was positive in 2 out of the 7 cases.(28.6% of cases)

The first patient was  a renal allograft recipient  who underwent a living donor transplant in 2018. Nine months post transplant he presented with graft dysfunction and was diagnosed to have BK virus associated nephropathy(BKVAN) on renal biopsy. He developed progressive graft dysfunction despite reduction of immunosuppression and lost his graft on subsequent follow up. Forty six months post transplant (and 3 years after the diagnosis of BKVAN) he presented with gross hematuria and was diagnosed on cystoscopy guided biopsy to have an urothelial cancer of the urinary bladder. The histopathology showed high grade invasive urothelial carcinoma with focal squamous differentiation.

 Immunohistochemistry for SV 40 showed diffuse positivity on the tumour cells whereas the non neoplastic urothelium did not stain for SV 40.

 He underwent a radical cysto-prostatectomy with ileal conduit. He had progressive renal dysfunction and he returned to dialysis in the post op period. Twenty four months post surgery he continues to be tumor free and is on maintenance hemodialysis.

The second patient was a live donor renal allograft recipient in 2007. Eight years post renal transplant he presented with painless gross hematuria and was diagnosed to have high grade transitional cell carcinoma. IHC for SV 40 was diffusely positive in the cancer tissue. He was advised a radical cystectomy however he was lost to follow up.

Conclusions:

In summary it is important to keep in mind that BKPyV associated UC can develop in the setting of a BKPyV associated nephropathy and careful follow-up with urine cytology and cystoscopy if needed, is necessary in such patients. In our series 28.6% of cases of urothelial cancers in the post renal transplant setting were associated with BK polyoma virus.

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.